Product type modeling / product catalogues

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Modeling of product types

  1. What are product types
  2. Modeling of product types
    1. Determine the values
    2. Create definitions
    3. Quantification by numbers on scales (units of measure)

1. What are product types

A product type is a kind of product that is manufacturer specific or is described in a product standard. Typically product types specify some of the values for characteristics whereas they leave degrees of freedom for values of other characteristics, possibly specified for more detailed subtypes. For example, a standard for a product type may not specify a specific color, thus leaving that as a degree of freedom; or a product type may specify a range of standard sizes, thus in fact specifying subtypes of specific sizes. Manufacturers models or brands are product types that are manufacturer specific.
Product types are to be distinguished from one-off designs. The latter are designs that are intended to be a specification for an individual real product. Designs of large facilities and specialized equipment are typically one-off designs. In those cases the designer(s) develop(s) an imaginary individual thing that is a specification of an idea of how a new real facility or equipment should be fabricated. Then a materialized real object is realized by making the real one conform the design.
When series of products of the same kind are to be fabricated, then the various realized individual products may not even have individual identifiers. Usually a collection or batch of such products will have a unique identifier. For example: ‘stainless steel M6 bolts’. In such cases the design is usually generalized and given a product type identifier, typically as a product type code. The product type (the identifier) and its distinguishing characteristics is typically included in a product (type) catalog of the manufacturer or supplier.

Nowadays product catalogs are usually made searchable via the websites of the suppliers. However, it is currently not possible to express one universal query that searches for product types in different systems of multiple suppliers and that reports the combined results in one report. Neither is it possible to integrate selected resulting models directly in someones own models, such as in designs. This is caused by the fact that every manufacturer and supplier uses its own data structure, terminology and corresponding software for storage, searching and reporting.
Universal search, combined reporting and direct integration of product type models in users models, becomes possible by modeling product types in Gellish.

Models of product types are extended definition models in which the product types may by definition be composed of particular kinds of parts and/or in which a number of characteristics are defined to have specific values or a limited range of (distinct) values. Models of product types are thus collections of statements that express that some product type has by definition as part a particular kind and/or has by definition as aspect a kind of characteristic with a particular value. This means that Gellish expressions will be used which phrases typically start with <is by definition…> or <has by definition…>. However, not all aspects of product types need to be specified completely, because there may still be some degrees of freedom (options) left open. For example, a product type may have a well defined form and material of construction, but the color of a product of such a type is a free choice.

2. Modeling of product types

2.1 Determine values for the definition of product types

The ‘user view’ of the definition of a product type consists of a list of values for characteristics (attributes) of product types that are subtypes of the same supertype.

For example the product type with the Material and Equipment Standard Code (MESC) catalogue item is given in . This product type is a subtype of a ‘lined flanged ball valve’. It is the first of a family of such valves that have different values for the same collection of characteristics (here called attributes).

Figure 1: User view on a specific product type definition

Note that this product type is a buyers specification in which the values that define a specific product type can still have some degrees of freedom by allowing for a range or for more than one option. This is illustrated in for the material of construction, where there are two allowed values for one aspect. In that case individual products or subtypes comply with the specification when its value for the material of construction is one of the values that is defined in the collection of values. For the ‘mandatory additional requirements’ there are also two requirements for the same aspect.

2.2. Create definitions for product types

  1. The information about a product type (often referred to as ‘attributes’) shall be
    distinguished in:
    – aspects that are possessed by such a product.
    – aspects that are possessed by a part of such a product.
    – information to which such a product shall comply.
    – other things that shall be related to such a product by a
    particular kind of relation.

Modeling of those distinct categories requires the use of different kinds of relations, and may require the creation of new objects, such as parts. The general structure of a model of an aspect that can be, shall be or is by definition possessed by a physical object, the possessor role of the physical object and the ‘possessed aspect’ role of the aspect is presented in Figure 2.

Figure 2: General structure of a model of an aspect that is possessed by a physical object.

This structure is used to specify the requirements for the product family (those requirements are used as a template for the creation of product types or catalogue items). The generic template for such requirements is illustrated in Figure 3..

Figure : 3 Requirements for a Product family (generic template)

The generic requirements consist of a core specification, in which new concepts occur that shall be defined as subtypes of concepts that are already available in the dictionary of the formal language. This is applicable for all concepts, but is illustrated only for two concepts!

For aspects that are actually aspects of parts or physical features of the physical object it is recommended to model not only the indirect relation of the aspect with the product type (the physical object), but also to model that a physical object is a part or feature of the product type and to define that the aspect shall be an aspect of the physical object that acts as part or feature.
This enables to map systems that do not support a composition structure to systems that support such a composition structure.

Note 1: The above generic model defines not only requirements such as:

product type shall have as aspect a aspect

However, this enables also to specify constraints for those aspects.

Those constraints are however not generally applicable for the kind of aspect as such, but only for the aspect as possessed by this product type. In other words: for the aspect in this role only. Therefore, the template relates a product type to an ‘intrinsic aspect’ (= an aspect in a particular kind of role) as follows:

product type shall have as intrinsic aspect a intrinsic aspect

Note 2: A supertype has a distinguishing aspect of which each subtype by definition has a qualitative
aspect (value). This can be expressed in text as a textual definition or it can be modeled by defining qualitative aspects of the subtype.

The above generic requirements model can be used as a generic template that is applied for kinds of products and several kinds of aspects to create requirements for a product family. An example of such a product family requirements model (a filled-in generic template) for a ‘lined flanged ball valve’ is given in Figure 4.

Figure 4: Example of a specification of requirements for a product family

The example specifies among others, that it is a requirement (in the applicable validity context) that a lined flanged ball valve shall have a DN nominal diameter. This implies that a subtype of intrinsic aspect shall be created, called ‘nominal diameter of lined flanged ball valve’ and the lined flanged ball valve shall be related to that subtype.
This shall be specified as follows:


Name of left hand object

UID of idea

UID of kind of relation

Name of kind of relation


Name of right hand object


lined flanged ball valve



shall have as possessed aspect a


DN nominal diameter of a lined flanged ball valve


DN nominal diameter of a lined flanged ball valve



is a kind of


nominal diameter of a valve

2.3 Quantification by numbers on scales (units of measure)

The example of Figure 4 illustrates that a template specification can define a list of allowed values, which is a list of qualitative (or quantitative) aspects. For example, for colors the allowed values may be red, green and blue, for nominal diameters the allowed values might be constrained to 15 mm, 20 mm, etc.
The latter qualitative aspects are qualitative kinds that have a name that is a combination of a number and a scale. Such a concept is definied by having a quantification relation with a number on a scale, in this example a length scale, such as mm. Such qualitative aspects need to be standardized as well in the dictionary of the formal language. This means that a number of concepts such as 15 mm, 20 mm, etc. are predefined concepts in the formal dictionary.
For example, the quantitative aspect ‘15 mm’ is defined in the formal dictionary as follows:


Name of left hand object

UID of idea

UID of kind of relation

Name of kind of relation


Name of right hand object

UID of UoM



15 mm



is a qualification of




15 mm



is by definition quantified on scale as equal to





Because they are defined already, including their mapping on scale to numeric values, the qualitative values can be used directly in the template specification, whereas the mapping to numbers on a scale can be retrieved from the formal dictionary as and when required.
In case such qualitative aspects are not yet present in the formal dictionary they can be added in the user environment in the same way as the above example.

After creation of a template all product types, aspects, qualitative aspects and relations types that are used shall be present in the formal dictionary or shall be expressed as subtypes of concepts in the formal dictionary.

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